How hard is the water in San Juan County, NM?
55.3 grains per gallon
A softener will pay its way here.
The median hardness measured in San Juan County, NM is 947 mg/L as calcium carbonate, which is 55.3 gpg. That is very hard on the USGS scale. It comes from 688 samples at 62 sites between 1990 and 2023, drawn from groundwater wells, which is what most taps and private wells in the county draw on.
How much it varies here
Half the sites came in between 10.7 and 68.1 gpg. The whole middle of that range gives the same answer, so a test of your own tap is unlikely to change it. Confidence in the county figure: high (how it is measured).
What to do next
At 55.3 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water.
More on sizing a softener for your household.
From 0.2 to 292.1 gpg
The softest single sample on record in San Juan County was 3 mg/L and the hardest 5,000 mg/L, a 1,667-fold gap. The top quarter of sites read above 68.1 gpg and the bottom quarter below 10.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 55.3 gpg, rivers and lakes 11.8 gpg
688 groundwater samples from 62 wells put the median at 947.3 mg/L. 1,027 surface samples from 128 sites put it at 201.3 mg/L. In San Juan County the wells come out 43.5 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 80,000-grain unit covers a week between regenerations. Expect about 1,209 lb of salt a year (31 bags of 40 lb, about $218), and roughly 2,346 gallons of regeneration water. Installed, most units run $1,000 to $4,500; spread over 15 years with salt, that is about $318 a year.
Sizing at 55.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 3,318 | 24,000 | 404 lb |
| 2 | 6,636 | 48,000 | 807 lb |
| 4 | 13,272 | twin tank | 1,615 lb |
| 6 | 19,908 | twin tank | 2,422 lb |
San Juan County against the rest of New Mexico
Among the 33 New Mexico counties with data, San Juan County is number 4 of 33 counting from the hardest. Across the whole country it is harder than 98% of counties.
Softest in New Mexico: Rio Arriba County at 2.3 gpg. Hardest: Chaves County at 116.2 gpg. Closest to San Juan County: Guadalupe County (59.9), De Baca County (61.9), Otero County (31.3).